- If you’ve ever wondered why chimps pee together, we now have answers.
Yawning is famously contagious. If you see someone yawn, you’re more likely than not to do so yourself, as is everyone else around you.
Now imagine if the same went for other bodily functions — like emptying your bladder.
That’s how it apparently works with chimpanzees. A new study has found that chimps like to pee together, because urination is contagious among them.
If a chimp sees another nearby chimp take a leak, there’s a high chance that it will open the floodgates as well. Mutual pissing becomes even more likely if the observing chimp is of a lower rank than the initial whizzer.
Researchers aren’t sure yet why this hierarchical common peeing takes place. They suspect it may be a way to maintain social cohesion or mark territory.
They need more answers, though. So, the biologists have no option but to keep staring at chimps, hoping to catch them peeing together.
That’s science for you, folks.
‘Nerve-racking’ Pee Research
The chimp pee study was published recently in the journal Current Biology. Its main author is Ena Onishi, a doctoral student from Kyoto University Wildlife Research Center.
As Japanese, Onishi is familiar with people going to use the restroom at the same time. The Japanese even have a word for it — they call it “tsureshon.”
While working with chimpanzees at the Kyoto University’s Kumamoto Sanctuary, Onishi noticed that they often tended to take a leak together. So, she decided to observe chimps peeing to figure out if there was some kind of regularity to the behavior.
As you do when you’re a chimp scientist.
Onishi and her team filmed more than 600 hours of video footage of the sanctuary’s 20 chimps (which are mostly male). They then got to watch through every last hour to record when, where, and why any chimp caught peeing did so.
Not only that, Onishi’s team constructed a computer simulation to model chimpanzee peeing behavior. You know, so that they could compare the simulated whizzing to real instances to verify data.
Onishi called this whole process “nerve-racking” — partially because at times she caught herself wondering what on earth she was doing.
“It was a bit overwhelming because I didn’t know if I would get meaningful results or if all that effort would end up being for nothing,” she told Scientific American.
Well, she certainly seems aware of watching chimps pee for hours on end is a bit unusual.
Chimp See, Chimp Do
So, what results did Onishi’s research yield? Well, we now have a fairly accurate model of contagious communal peeing among chimpanzees.
Let’s imagine a group of chimps and call one of them Chimp A. If Chimp A decides to pee, any chimp around it is more likely to also urinate within 60 seconds than if they were alone.
However, this is highly dependent on distance between the chimps. If the chimps are within an arms reach of each other, mutual peeing is almost guaranteed; if they’re 10 feet away from each other, they’re much less likely to take a leak together.
That’s fascinating, as far as chimp urination goes. However, there’s another element at play when it comes to mutual peeing — social status.
Initially, Onishi expected that the chimps would be morel likely to pee together if they were close friends, kind of like humans do with yawning. However, the situation is actually the exact opposite.
“We observed a clear influence of social rank, with lower-ranking individuals being more likely to follow the urination of others,” explained Onishi.
If Chimp A is a big cheese, lower-ranking chimps around it are more likely to evacuate their bladders together with it. However, if Chimp A is last in the pecking order, it will have to pee all on its lonesome.
What a cruel world we live in.
To Pee Is to Rule
Of course, now that we know how communal chimpanzee pissing happens, the big remaining question is why. That’s where we’re left without a solid answer.
This was the first ever study done on chimp peeing (which is honestly kind of surprising). As such, there are many things that Onishi’s team simply couldn’t look into.
For instance, they don’t know whether the communal behavior happens in the wild. However, the research team can make some educated guesses.
Due to the hierarchical structure of peeing together, Onishi’s team suspects that it may be a way to enforce the chimp group’s social structure. By peeing with the leader, the other chimps show submission to its will.
Additionally, chimpanzee groups in the wild tend to move around a lot, with the decision to relocate made by the dominating chimp. As such, the call-and-response peeing might be a way for the leader chimp to say, “We’re hitting the road, everybody go to the bathroom.”
In the similar vein, the entire chimp group emptying their bladders in unison would leave quite a strong scent mark on the ground. As such, it may be way for the leaving group to declare the spot as their turf in case they feel like coming back.
More research is needed before anybody can make any conclusive theories, though. So, it’s back to watching videos of peeing chimps for Onishi’s team.